A sizer is a software tool, for use in relation to a given apparatus, that operates upon (and optionally also gathers) information that is characteristic of a user's specifications for the given apparatus to estimate (as its name suggests) one or more values of parameters for the given apparatus sufficient to accommodate the user's requirements. For example, a server-sizing tool according to the Background Art provides sizing guidelines for the Microsoft® brand, Exchange model of messaging and collaboration server. Among the data generated by the Background Art server sizing tool are estimates of the total number of servers needed for a given user's requirements and a total amount of storage space demanded by the installation under consideration.